i want to show related posts by tag name However i got the error " get() returned more than one Tag -- it returned 2!"
def post_detail(request,slug):
post=get_object_or_404(Post,slug=slug)
comments=Comment.objects.filter(post=post,reply=None,statusc=2).order_by('-date')
comment_count=len(Comment.objects.filter(post=post, statusc=2))
tag=get_object_or_404(Tag,post=post)
related_item=Post.objects.filter(tag__tag_name__icontains=tag.tag_name,status=2).order_by('-created_date').distinct()[:3]
You can just query like:
def post_detail(request,slug):
post=get_object_or_404(Post,slug=slug)
comments=Comment.objects.filter(post=post,reply=None,statusc=2).order_by('-date')
comment_count=len(comments)
related_items = Post.objects.filter(
tag__post=post
).order_by('-created_date').distinct()[:3]
# ...
Or if you want to exclude the current post:
def post_detail(request,slug):
post=get_object_or_404(Post,slug=slug)
comments=Comment.objects.filter(post=post,reply=None,statusc=2).order_by('-date')
comment_count=len(comments)
related_items = Post.objects.exclude(pk=post.pk).filter(
tag__post=pos
).order_by('-created_date').distinct()[:3]
# ...
It is also better to perform a len(..) on the comments, since that will result in making a query to fetch the comments, whereas using two separate queries, will hit the database twice.
As per documentation, get() is used for retrieving 1 item. If there are multiple items, here there could be multiple tags used in single Post, it will throw error.
So, you can change it like this:
tags=Tag.objects.filter(post=post)
related_item=Post.objects.filter(tag__in=tags,status=2).order_by('-created_date').distinct()[:3]
Related
I'm getting an unexpected result using icontains in my get_or_create call.
Take the following example:
>>>team_name = "Bears"
>>>Team.objects.get(name__icontains=team_name) # returns DoesNotExist as expected
>>>team, created = Team.objects.get_or_create(name__icontains=team_name)
>>>print(created) # Prints True as expected
>>>print(team.name) # Prints an empty string!
Why does this create a team with a blank name rather than "Bears"? The reason I'm using get_or_create here is that if a subsequent user posts something like "BearS" I want to get the correct team, not create a duplicate team with incorrect capitalization.
I think here you should split the get() and create() functionalities instead of using get_or_create(), because the __icontains lookup works for get() only.
Try doing something like this:
>>> team_name = 'Bears'
>>> teams = Team.objects.filter(name__icontains=team_name)
# This will filter the teams with this name
>>> team = teams.first() if teams.exists() else Team.objects.create(name=team_name)
# Now your team is the first element of your previous query (it returns a QuerySet with single element) if it exists
# Otherwise, you create a new Team.
Another option besides wencakisa's answer is to include the defaults parameter in get_or_create, because Django strips lookups containing the __ separator. See answers to this question.
The code would be:
Team.objects.get_or_create(
name__icontains=team_name,
defaults = {
"name": team_name
}
)
The right way to do it is using Django's function get_or_create(). But instead of "icontains", you should use "iexact" (), unless you want an exact match, in wich case you should use just "exact":
Team.objects.get_or_create(
name__iexact=team_name,
defaults = {
"name": team_name
}
)
Outside "defaults" you should put your search terms. If the objects doesn't exist, you should write your creation terms inside 'defaults'
I want to use a database query to generate my URL configuration. Something like:
states = State.objects.all().values_list('pk', flat=True)
And then a regex like:
(r'^state/(?P<state>' + '|'.join(states) + ')/$'
The idea is that I can have URLs like:
/state/ca/
/state/az/
Etc.
The problem is that when I do syncdb, the query above fails, throwing a DatabaseError.
Is there a good way to do this? I've tried the obvious change, which would be:
try:
states = State.objects.all().values_list('pk', flat=True)
except DatabaseError:
# First sync, use dummy data
states = []
But this doesn't work because the exception is thrown at the regex, not at the query definition.
Ideas?
Why do you need to constrain this in the URL pattern itself? Much better to accept all two-letter codes, and check in the view.
(r'^state/(?P<state_code>\w{2})/$'
def view_state(request, state_code):
state = get_object_or_404(State, pk=state_code)
I'm trying to render a form with a combo that shows related entities. Therefore I'm using a ModelChoiceField.
This approach works well, until I needed to limit which entities to show. If I use a simple query expression it also works well, but things break if I use a raw SQL query.
So my code that works, sets the queryset to a filter expression.
class ReservationForm(forms.Form):
location_time_slot = ModelChoiceField(queryset=LocationTimeSlot.objects.all(), empty_label="Select your prefered time")
def __init__(self,*args,**kwargs):
city_id = kwargs.pop("city_id") # client is the parameter passed from views.py
super(ReservationForm, self).__init__(*args,**kwargs)
# TODO: move this to a manager
self.fields['location_time_slot'].queryset = LocationTimeSlot.objects.filter(city__id = city_id )
BUT, if I change that to a raw query I start having problems. Code that does not work:
class ReservationForm(forms.Form):
location_time_slot = ModelChoiceField(queryset=LocationTimeSlot.objects.all(), empty_label="Select your prefered time")
def __init__(self,*args,**kwargs):
city_id = kwargs.pop("city_id") # client is the parameter passed from views.py
super(ReservationForm, self).__init__(*args,**kwargs)
# TODO: move this to a manager
query = """SELECT ts.id, ts.datetime_to, ts.datetime_from, ts.available_reserves, l.name, l.'order'
FROM reservations_locationtimeslot AS ts
INNER JOIN reservations_location AS l ON l.id = ts.location_id
WHERE l.city_id = %s
AND ts.available_reserves > 0
AND ts.datetime_from > datetime() """
time_slots = LocationTimeSlot.objects.raw(query, [city_id])
self.fields['location_time_slot'].queryset = time_slots
The first error I get when trying to render the widget is: 'RawQuerySet' object has no attribute 'all'
I could solve that one thanks to one of the commets in enter link description here, by doing:
time_slots.all = time_slots.__iter__ # Dummy fix to allow default form rendering with raw SQL
But now I'm getting something similar when posting the form:
'RawQuerySet' object has no attribute 'get'
Is there a proper way to prepare a RawQuerySet to be used by ModelChoiceField?
Thanks!
Are you sure you actually need a raw query there? Just looking at that query, I can't see any reason you can't just do it with filter(location__city=city_id, available_reserves__gte=0, datetime_from__gt=datetime.datetime.now()).
Raw query sets are missing a number of methods that are defined on conventional query sets, so just dropping them in place isn't likely to work without writing your own definitions for all those methods.
I temporarily fixed the problem adding the missing methods.
The way I'm currently using the ModelChoiceField I only needed to add the all() and get() methods, but in different scenarios you might need to add some other methods as well. Also this is not a perfect solution because:
1) Defining the get method this way migth produce incorrect results. I think the get() method is used to validate that the selected option is within the options returned by all(). The way I temporarily implemented it only validates that the id exists in the table.
2) I guess the get method is less performant specified this way.
If anyone can think of a better solution, please let me know.
So my temporary solution:
class LocationTimeSlotManager(models.Manager):
def availableSlots(self, city_id):
query = """SELECT ts.id, ts.datetime_to, ts.datetime_from, ts.available_reserves, l.name, l.'order'
FROM reservations_locationtimeslot AS ts
.....
.....
MORE SQL """
time_slots = LocationTimeSlot.objects.raw(query, [city_id])
# Dummy fix to allow default form rendering with raw SQL
time_slots.all = time_slots.__iter__
time_slots.get = LocationTimeSlot.objects.get
return time_slots
I've been using the built-in Django comments system which has been working great. On a particular page I need to list the latest X comments which I've just been fetching with:
latest_comments =
Comment.objects.filter(is_public=True, is_removed=False)
.order_by('submit_date').reverse()[:5]
However I've now introduced a Boolean field 'published' into the parent object of the comments, and I want to include that in the query above. I've tried using the content_type and object_pk fields but I'm not really getting anywhere. Normally you'd do something like:
Comment.objects.filter(blogPost__published=True)
But as it is not stored like that I am not sure how to proceed.
posts_ids = BlogPost.objects.filter(is_published=True).values_list('id', flat=True) #return [3,4,5,...]
ctype = ContentType.objects.get_for_model(BlogPost)
latest_comments = Comment.objects.filter(is_public=True, is_removed=False, content_type=ctype, content_object__in=posts_ids).order_by('-submit_date')[:5]
Comments use GenericForeignKey to store the relation to parent object. Because of the way generic relations work related lookups using __<field> syntax are not supported.
You can accomplish the desired behaviour using the 'in' lookup, however it'll require lot of comparisons when there'll be a lot of BlogPosts.
ids = BlogPost.objects.filter(published=True).values_list('id', flat=True) # Get list of ids, you would probably want to limit number of items returned here
content_type = ContentType.objects.get_for_model(BlogPost) # Becasue we filter only comments for BlogPost
latest_comments = Comment.objects.filter(content_type=content_type, object_pk__in=ids, is_public=True, is_removed=False, ).order_by('submit_date').reverse()[:5]
See the Comment model doc for the description of all fields.
You just cannot do that in one query. Comments use GenericForeignKey. Documentation says:
Due to the way GenericForeignKey is implemented, you cannot use such
fields directly with filters (filter() and exclude(), for example) via
the database API.
Admin actions can act on the selected objects in the list page.
Is it possible to act on all the filtered objects?
For example if the admin search for Product names that start with "T-shirt" which results with 400 products and want to increase the price of all of them by 10%.
If the admin can only modify a single page of result at a time it will take a lot of effort.
Thanks
The custom actions are supposed to be used on a group of selected objects, so I don't think there is a standard way of doing what you want.
But I think I have a hack that might work for you... (meaning: use at your own risk and it is untested)
In your action function the request.GET will contain the q parameter used in the admin search. So if you type "T-Shirt" in the search, you should see request.GET look something like:
<QueryDict: {u'q': [u'T-Shirt']}>
You could completely disregard the querystring parameter that your custom action function receives and build your own queryset based on that request.GET's q parameter. Something like:
def increase_price_10_percent(modeladmin, request, queryset):
if request.GET['q'] is None:
# Add some error handling
queryset=Product.objects.filter(name__contains=request.GET['q'])
# Your code to increase price in 10%
increase_price_10_percent.short_description = "Increases price 10% for all products in the search result"
I would make sure to forbid any requests where q is empty. And where you read name__contains you should be mimicking whatever filter you created for the admin of your product object (so, if the search is only looking at the name field, name__contains might suffice; if it looks at the name and description, you would have a more complex filter here in the action function too).
I would also, maybe, add an intermediate page stating what models will be affected and have the user click on "I really know what I'm doing" confirmation button. Look at the code for django.contrib.admin.actions for an example of how to list what objects are being deleted. It should point you in the right direction.
NOTE: the users would still have to select something in the admin page, otherwise the action function would never get called.
This is a more generic solution, is not fully tested(and its pretty naive), so it might break with strange filters. For me works with date filters, foreign key filters, boolean filters.
def publish(modeladmin,request,queryset):
kwargs = {}
for filter,arg in request.GET.items():
kwargs.update({filter:arg})
queryset = queryset.filter(**kwargs)
queryset.update(published=True)